It sounds wrong. E-cigarettes should be banned, says a long list of prestigious anti-tobacco groups including the American Cancer Society and the American Lung Association. But a federal court has stymied FDA efforts to keep them off the U.S. market.

Meanwhile, more and more Americans are buying e-cigarettes. And many of them say they’ve used the nicotine vaporizers to quit smoking real cigarettes, according to a new survey by Michael B. Siegel, MD, MPH, of Boston University School of Public Health.

“If you look at the evidence, these are a lot safer than regular cigarettes — and they are effective for some people in helping them quit smoking cigarettes,” Siegel tells WebMD.

Siegel and colleagues emailed surveys to 5,000 first-time buyers of Blu brand e-cigarettes. Replies came back from 222 of them (4.5%), of whom 216 said they were smokers.

Six months after their purchase, 31% of these smokers said they’d quit cigarettes and two-thirds of them said they’d cut back on the number of cigarettes they smoked. A third of those who’d quit smoking also quit using e-cigarettes.

Those are pretty impressive numbers, as only about 18% of smokers who quit actually do so for at least six months. But Siegel notes that a survey like this doesn’t prove anything. All it can do is hint that maybe, just maybe, e-cigarettes can do some good.

Tobacco policy expert Michel Eriksen, ScD, director of the Georgia State University institute of public health, agrees with Siegel on this point. Eriksen, who was not involved in the Siegel study, is a former director of the CDC’s Office on Smoking and Health.

It might have value. “The potential for electronic cigarettes in being helpful in smoking cessation is real but unestablished yet,” Eriksen says.

What’s needed is proof from rigorous studies, Siegel says. Proof that e-cigarettes really do help people quit smoking. And proof that e-cigarettes can safely be used as quit-smoking devices.

E-cigarettes use a battery-driven heater to vaporize liquid nicotine and flavoring from a small cartridge. To make the vapor visible, the cartridges also dispense propylene glycol (PEG), commonly used for theatrical “smoke.” Users puff or inhale the vapor from a mouthpiece.

To almost everybody, that sounds like a device for delivering nicotine. But because the nicotine is ultimately derived from tobacco plants, a federal court has ruled that e-cigarettes are — legally speaking — tobacco products and not nicotine-delivery devices.

Since they are tobacco products, the court ruled, the FDA lacks authority to regulate e-cigarettes as drugs or devices as long as they are marketed without claims of therapeutic effect.